Regulation of gonococcal sialyltransferase, lipooligosaccharide, and serum resistance by glucose, pyruvate, and lactate

Abstract

Strain F62 of Neisseria gonorrhoeae gonococci (GC) is sensitive to normal human serum unless CMP-Nacetylneuraminic acid (CMP-NANA) is present. NANA is transferred primarily to a 4.5-kDa lipooligosaccharide (LOS) structure by a GC sialyltransferase (Stase). We investigated LOS and Stase expression and serum resistance in strain F62 grown in different carbon sources and growth conditions. Pyruvate-grown GC expressed 1.9-to 5.6-fold more Stase activity than did glucose-grown GC, whereas lactate-grown GC generally expressed intermediate Stase activities. Broth-grown GC expressed two-to fourfold more Stase activity than did plate-grown GC in all carbon sources. Pyruvate-or lactate-grown GC expressed significantly more of the sialylateable 4.5-kDa LOS species than did glucose-grown GC. Anaerobically, the 4.5-kDa LOS species was expressed in greater quantity than the 4.9-kDa N-acetyl galactosamine-terminating species in all carbon sources. Pyruvate-grown GC also incorporated up to threefold more radiolabelled CMP-NANA onto the 4.5-kDa LOS species than did glucose-grown GC. In serum resistance studies, pyruvate-grown GC were 6.5-to 16.1-fold more serum resistant than glucose-grown GC at limiting CMP-NANA concentrations (1.56 to 12.50 g/ml). Taken together, these results indicate that gonococcal expression of Stase activity is up-regulated by growth in pyruvate or lactate, which correlates with enhanced expression of the sialylateable 4.5-kDa LOS and, for growth in pyruvate, correlates with enhanced sialylation of gonococcal LOS and greater serum resistance. In different in vivo niches, gonococcal LOS sialylation, serum resistance, and interaction with host cells can be highly regulated.

Expression of sialyltransferase is not required for interaction of Neisseria gonorrhoeae with human epithelial cells and human neutrophils

“…Other variants and their Stase phenotypes are listed below (see Table 1). GC were grown on GC agar (GCA) or inoculated into GC broth (GCB) with supplements containing pyruvate, lactate, or glucose as described previously (23). CMP-NANA (25.0 to 50.0 g/ml; Sigma) was added as needed from a stock concentration of 5.0 mg/ml, as described previously (23).…”

“…Extraction and measurement of Stase activity. Stase was extracted and measured as described previously (21,23), except as indicated in the footnotes to Tables 1 and 2. Background counts, always Ͻ1% of WT Stase activity, were subtracted, and negative values were set to zero.…”

“…GC (3 ϫ 10 8 ) grown with or without CMP-NANA was digested with proteinase K as described previously (14). LOS was analyzed by Tricine-sodium dodecyl sulfate-polyacrylamide gel electrophoresis (Tricine-SDS-PAGE) (17,23,35) and silver stained (41).…”

“…These results suggest that reduction in the sialylation of LOS is required prior to interaction with human cells and that resialylation occurs before exit of GC into the extracellular environment (43); the exact mechanism(s) is unclear. The recent observations that serum resistance and expression of Stase activity are enhanced by growth of GC with lactate or pyruvate (23,26) may help in our understanding of the sialylation states of in vivo-grown GC.…”

Lactate causes changes in gonococci including increased lipopolysaccharide synthesis during short-term incubation in media containing glucose

“…McGee and R.F. Rest [4]. When strain F62 was incubated separately with either glucose, pyruvate or lactate (20 mM) in GC broth (Difco) for 3 h, sialyltransferase contents of the pyruvate-and lactate-grown gonococci were twofold higher than for glucose-grown organisms and the proportion of their sialylatable to non-sialylatable LPS components was also increased.…”